Tubing anchor and catcher

ABSTRACT

A tubing anchor and catcher set by rotary motion of a threaded mandrel employs slip-cone rings on the mandrel to move wedge slip members outward into engagement with the casing. The wedge slip members are interfitted with friction dragblock members frictionally engaging the casing. Springs confined between each wedge slip member and its respective dragblock member hold the wedge slip member in retracted position against the mandrel surface and move the dragblock member into casing engagement while running in the hole. The wedge slip members are carried directly on the slip-cone rings without any intermediate supporting member. An emergency release is provided by a shear ring between the mandrel and one of the slip-cone rings. In the modified form of the device, an emergency release is provided by continued turning of the mandrel in the same direction used to set the wedge slip members, to shear the ring.

United States Patent Conrad 1451 May 23, 1972 [54] TUBING ANCHOR AND CATCHER [21] Appl.No.: 69,664

Primary Examiner-James A. Leppink Attorney-Lyon & Lyon [57] ABSTRACT A tubing anchor and catcher set by rotary motion of a threaded mandrel employs slip-cone rings on'the mandrel to move wedge slip members outward into engagement with the casing. The wedge slip members are interfitted with friction dragblock members frictionally engaging the casing. Springs confined between each wedge slip member and its respective dragblock member hold the wedge slip member in retracted position against the mandrel surface and move the dragblock member into casing engagement while running in the hole. The wedge slip members are carried directly on the slip-cone rings without any intermediate supporting member. An emergency release is provided by a shear ring between the mandrel and one of the slip-cone rings. In the modified form of the device, an emergency release is provided by continued turning of the mandrel in the same direction used to set the wedge slip members, to shear the ring.

521 U.S.Cl ..166/216 511 ..E21b23/00 [58] FieldoiSearch ..166/216,217,138,139, 140

[56] References Cited uumzo STATES PATENTS 3,279,544 10/1966 Tauschetal ..166/216 3,026,941 3/1962 Muse ..166/216 3,295,606 1/1967 Bumpers ..166/216 3,338,308 8/1967 Ellistonetal. .....166/216 3,391,742 7/1968 Davis ..166/189 3,412,801 11/1968 Young... .....166/139 3,077,933 2/1963 Bigelow.. .....l66/2l7 3,080,924 3/1963 Baker eta] ..166/212 PATENTED m 2 3 I972 SHEET 2 OF 3 FIG, 4.

INVENTOR MA BT/A/ 5. CONE/4 0 A rrae/ve V9 PATENTEDHAY 2 3 m2 SHEET 3 0F 3 INVENTOR MAE/7N 5- GOA/640 ATTOE/V VS TUBING ANCHOR AND CATCl-[ER This invention relates to tubing anchors and tubing catchers of the type used in oil wells to hold the tubing stationary while a pump carried in the tubing is reciprocated by sucker rods extending to the surface through the interior of the tubing. The tubing-anchor device is positioned near the pump to prevent cyclical vertical movement of the tubing as the sucker rods reciprocate. If the tubing should break in two for any reason, the anchor serves as a catcher to prevent the portion of the tubing below the break from falling down into the hole, with resulting damage.

The device of the present invention employs a plurality of grip assemblies of novel design. Each grip assembly has a dragblock member and a slip member which are interfitted so that one overlies a part of the other, and with springs interposed between them to move them in radially opposite directions. Such grip assembly has an inherent advantage in that it produces a friction rotational drag on the mandrel while it is running in the hole to minimize the hazard of inadvertent or accidental setting of the anchor. A housing floats on the grip assemblies and the wedge slip members of such assemblies are supported above and below by slip-cone rings mounted on the mandrel. There is no intermediate load-carrying member. The dragblock wedge slip arrangement produces the greatest friction resistance when the wedge slips are being extended. This feature makes it possible to secure a reliable solid setting of the tool in the casing. All working parts are securely enclosed within the housing and there are no loose parts which can corrode away or shake off in the hole. Moreover, the device is so designed as to vent gas through the interior of the anchor device as well as around the outside thereof, thus reducing the restrictive effect of the anchor device on gas passing upward through the annulus between the casing and the tubing.

Other and more detailed objects and advantages will appear hereinafter.

In the drawings:

FIG. 1 is a side elevation showing a preferred embodiment of this invention, with the parts in position for running into the hole.

FIG. 2 is a sectional elevation taken substan-tially on the lines 22 as shown in FIG. 1.

FIG. 3 is a sectional view similar to FIG. 2, showing the parts in anchored position in the casing.

FIG. 4 is a sectional view similar to FIG. 2, showing the parts sheared free for withdrawal of the device from the cas- FIGS. 5, 6, 7 and 8 are transverse sectional elevations taken on lines 5-5, 66, 77 and 88, respectively, as shown in FIG. 2.

FIG. 9 is an exploded view of the dragblock member, slip member, and springs which make up one of the grip assemblies.

FIG. 10 is a perspective view showing the part which forms the lower end of the housing.

Referring to the drawings, the tubing anchor-catcher generally designated 10 includes a central tubular mandrel 11 having threads 12 and 13 at its upper and lower ends for connecting it into a string of tubing by means of tubing collars 14. The tubing anchor-catcher 10 is adapted to be lowered into the well through the interior of the well casing 15.

The elongated annular housing 16 is provided with a plurality of window openings 17 through which project the grip assemblies generally designated 18. Each of these assemblies 18 includes a slip member 20 having a pair of axially spaced wedge elements 21 connected by an internal wall 22. Each grip assembly 18 also includes a dragblock member 24 having parallel legs 25 connected by an integral transverse bridge 26. The bridge 26 overlies the wall 22 of the slip member 20, and a plurality of compression coil springs 27 are interposed between the bridge 26 and the wall 22. Sockets 28 and 29 in the slip member 20 and dragblock member 24 receive the ends of the springs 27. The springs 27 act to move the members 20 and 24 radially in opposite directions, thereby urging the slip member 20 against the outer surface 31 of the mandrel 11 and urging the dragblock member 24 into frictional engagement with the inner surface 32 of the casing 15.

The inner surface 33 (FIG. 6) of the slip member 20 is concave for frictional contact with the mandrel surface 31. The outer faces 34 of the wedge portion 21 of the slip member 20 are transversely curved and serrated to provide wicker teeth for engagement with the inner surface 32 of the casing 15. The outer face 35 of the dragblock member 24 is smooth and is curved for frictional engagement with the same casing surface 32. The face 35 includes portions of the legs 25 and bridge 26. The parallel legs 25 in the dragblock member 24 define axially spaced slots 36 which receive the side edges of the wedge portions 21 of the slip member 20. In the absence of the casing 15, the laterally projecting lugs 37 on the dragblock member 24 engage the inner surface 38 of the housing 16 under force of the springs 27 to limit the extent of movement of the dragblock member 24 in a radially outward direction.

The grip assemblies 18 each including the slip member 20, dragblock member 24 and springs 27, just described, are each mounted between slip-cone rings 40 and 41 which are axially spaced on the mandrel 11. The slip-cone ring 40 is provided with right-hand internal threads 42 which engage the righthand external threads 43 provided on the outer surface of the mandrel 11. The ring 40 has three circumferentially spaced portions 44 each having a conical outer surface 45. The slip-' cone ring 41 has three similar conical portions 46, and these conical portions 45 and 46 are received by the mating conical surfaces 47 at opposite ends of the slip members 20. The ring 41 is mounted to turn on the mandrel and is held against axial movement thereon by means of a shear pin 49 mounted in the ring and projecting into a circumferential groove 50 provided on the outer surface 31 of the mandrel 11. A shear ring 73 encircles the mandrel within theslip-cone ring 41 to prevent downward movement of the ring 41 with respect to the mandrel 11 during normal operations.

Means are provided for preventing relative turning motion between the housing 16 and the slip-cone rings 40 and 41, and, as shown in the drawings, this means includes radially projecting lugs 52 and 53 provided on the slip-cone rings adjacent the large ends of their conical surfaces 45 and 46, respectively. The lugs 52 project radially into slots 54 provided in the housing 16 at the upper ends of the window openings 17 (see FIGS. 1 and 5 The lugs 53 on the slip-cone ring 41 project into similar slots 55 formed in the housing end member 56.

As best shown in FIG. 10, the housing end member 56 is provided with three pairs of circumferentially spaced upstanding fingers 57, each pair of fingers 57 having an axial slot 55 defined between them. The housing 16 has three circumferentially spaced downward extending projections 58 (FIGS. 2 and 8) each of which has an outer threaded surface 59 and an inner cylindrical surface 60. An assembly ring 61 having internal threads 62 engages the external threads 59 on the mandrel projections 58 and serves to clamp the end member 56 to the lower end of the housing 16. Relative rotation between the housing 16 and the end member 56 is prevented by the interfitting relationship of the projections 53 and the fingers 57. The end member 56 functions as an integral part of the housing 16.

For purposes of assembly of the slip members 20, springs 27 and dragblock member 24, a small radial hole 65 (FIG. 9) is provided in the bridge 26 of the member 24, and a cap screw 66 is inserted through this hole 65 to engage the threaded opening 67 provided in the slip member 20. The parts 20 and 24 and the springs 27 interposed between them form an assembly which can be handled as a unit for installation through the interior of the housing 16, and prior to installation of the mandrel 11. When the assembly of the mandrel, slip-cone rings 40 and 41, grip assemblies 18, housing 10 and end member 56 has been completed, and prior to installation of the device 10 into a well casing 15, the cap screws 66 are removed. Outward movement of the dragblock members 24 under force of the springs 27 is limited by contact of the lugs 37 with the interior surface 38 of the housing 16.

In operation, the parts of the tubing anchor-catcher are assembled as shown in FIGS. 1 and 2 and are lowered into the casing on the string of tubing, not shown. The dragblock members 24 have sliding contact with the inner surface 32 of the casing 15 as the device is lowered into position. The downward force on the tubing string is applied to the mandrel 1 1, and this force is transmitted through the threads 42 and 43 to the upper slip-cone ring 40, and then to the slip members through the mating conical surfaces 45 and 47. The springs 27 hold the inner surface 33 of the slip members 20 frictionally against the outer surface 31 of the mandrel l l to prevent rotation of the mandrel 11 with respect to the housing 16 as the device travels downward through the casing 15, thus minimizing the hazard of premature setting. During this downward movement the dragblock members 24 are pushed by the slip members 20. The slip members 20 push downward against the upper ends of the fingers 57 on the housing end member 56, thereby moving the housing 16 downward with the mandrel 11.

When the device has reached the desired depth, lowering movement of the tubing is terminated and the tubing is then turned to the left in a counterclockwise direction, as viewed from the top. This turning movement as communicated to the mandrel 11 through the tubing string causes the mandrel to move the upper slip-cone member 40 downward along the threads 42 and 43. Turning movement of the mandrel 11 does not turn the slip-cone member 40 along with it because the latter is prevented from turning by reason of the engagement of the lugs 52 in the slots 54 of the housing 16. The housing does not turn because it is restrained by the contact of the dragblock members 24 in the casing and by the side edges of the window apertures 17. Continued turning movement of the mandrel l 1 brings the parts to the anchored position shown in FIG. 3, wherein the wicker teeth of the serrated outer surfaces 34 of the slip members 20 bite into the inner surface 31 of the casing 15. This outward movement of the slip members 20 is caused by the slip-cone member 40 moving downward with respect to the slip-cone member 41 to cause the conical surfaces 45, 47 and 46, 47 to move the slip members 20 radially outward, further compressing the springs 27. With the parts in the position shown in FIG. 3, the mandrel 11 and hence the tubing string attached to it are prevented from moving up or down with respect to the casing 15. It will be noted that the greatest frictional resistance provided by the dragblock members 24 occurs when the slip members 20 are being extended. This is a very advantageous feature, leading to a good solid set of the anchor.

While the tubing anchor-catcher device 10 is being lowered through the casing 15, as shown in FIG. 2, and while it is in the anchored position shown in FIG. 3, gas in the casing may pass upward around the outside of the housing 16 in the arcuate spaces between the grip assemblies 18, and gas passageways are also provided inside the housing 16. Thus, clearance channels 68 are formed between the end member 56 and the outer surface of the mandrel, and clearance channels 69 and 70 are formed on the outer surfaces of the slip-cone rings 41 and 40, and clearance passages 71 are formed at the upper end of the housing 16 at locations circumferentially spaced from the slots 54. Accordingly, gas passageways are formed within the interior of the housing 16 from one end to the other. The anchor device thus provides a minimum of restriction to the flow of gas upward in the annulus between the tubing and the casing.

The device 10 serves as an anchor to prevent movement of the tubing string, and also serves as a tubing catcher in the event that the tubing string should part in two, for any reason. If the tubing should part above the device 10, the lower portion is automatically held against falling down through the interior of the casing, with consequent damage.

In the anchored position, the housing 16 floats" on the grip assemblies 18 which are supported above and below directly by the slip-cone rings. There is no intermediate load-carrying member. All working parts are securely enclosed within the housing. There are no loose parts on the outside that can corrode away or shake off in the hole.

When it is desired to remove the tubing anchor-catcher device 10 from the hole, the tubing is turned in a right-hand direction, clockwise as viewed from the top, and this causes the mandrel 11 to move the upper slip-cone ring 40 in an upward direction, to move the parts from the position shown in Fig. 3 to the position shown in FIG. 2. Relative turning movement of the mandrel 11 and slip-cone ring 40 along the threads 42 and 43 ceases when the pin 75 on the ring 40 strikes the radial abutment 76 on the mandrel. The springs 27 return the slip members 20 to the retracted position against the outer surface of the mandrel 11, and the device is then lifted out of the hole. In the event that such right-hand rotation fails to release the device 10, however, an emergency release action is provided by pulling upward on the tubing string and mandrel 11 with a sufiiciently heavy pull to shear the shear ring 73, thereby moving the parts to the position shown in FIG. 4. Shearing of the ring 73 and the pin 49 moves the lower slip-cone ring 41 downward with respect to the upper slip-cone ring 40, thereby permitting the slip members 20 to be moved to retracted position under action of the springs 27. The device may then be withdrawn upward from the hole.

In a modified form of the invention, the device is identical in appearance with that shown and described above except that the threads 42 and 43 connecting the upper slip-cone ring 40 to the mandrel 11 are formed as left-hand threads. In this modified device, setting of the tool in anchored position is accomplished by right-hand rotation of the tubing string and mandrel. After a period of use when it is desired to remove the device from the well, right-hand rotation of the mandrel is again applied. Sufficient force is developed to shear the ring 73 and to permit subsequent withdrawal of the device from the well hole. This form of the device with the left-hand threads is useful in slanted or crooked holes where a combination of tension and torque on the tubing may be the only way to produce sufiicient force at the tool to shear the ring.

Having fully described my invention, it is to be understood that I am not to be limited to the details herein set forth but that my invention is of the full scope of the appended claims.

I claim:

1. In a tubing anchor-catcher for securing a string of tubing within a well casing, the combination of: a tubular mandrel adapted to be connected to a tubing string; a plurality of grip assemblies mounted on said mandrel; each of said grip assemblies having a slip member provided with a pair of axially spaced wedge portions connected by an internal wall portion, the wedge portions each having a serrated outer face, each assembly also having a dragblock member provided with an outer face adapted to frictionally engage the inner surface of a well casing, means limiting the extent of outward movement of the dragblock member in the absence of the casing, resilient means confined between said wall portion of the slip member and said dragblock member acting to urge said slip member inwardly toward said mandrel and said dragblock member outward against the casing; and means for moving the slip members radially outward against the action of said resilient means and into gripping contact with the casing.

2. In a tubing anchor-catcher for securing a string of tubing within a well casing, the combination of: a tubular mandrel adapted to be connected to a tubing string; a plurality of grip assemblies mounted on said mandrel; each of said grip assemblies having a slip member provided with a pair of axially spaced wedge portions connected by an internal wall portion, the wedge portions each having a serrated outer face, each assembly also having a dragblock member provided with an outer face adapted to frictionally engage the inner wall surface of a well casing, one of the members having at least one axially extending slot slidably receiving side edges of the other member, said dragblock member having a portion thereof laterally overlying said internal wall portiommeans limiting the extent of outward movement of said dragblock member in the absence of the casing, resilient means confined between said wall portion of the slip member and the overlying portion of said dragblockmember acting to urge said slip memberinward toward said mandrel and said dragblock-member outward against the casing; and means mounted on the mandrel for moving the slip members radially outwardagainst the action of said resilient means and into gripping contact with the casing.

3. The device set forth in claim 2 in which the dragblock member is provided with at least one slot which slidably receives side edges of one of the wedge portions of theslip member.

4. The device set forth in claim '2 in which the dragblock member has two axially spaced slots slidably receiving side edges of the wedge portions of the slip member.

5. The combination set forth in claim 2 in which said internal wall portion of said slip member has an inner .surface adapted for frictional contact with the outer surface of said mandrel.

6. In a tubing anchor-catcher forof a string of tubing within a well casing, the combination of: a tubular mandrel having ends adapted to be connected to a tubing string; an annular housing mounted to turn on the mandrel and provided with window; a plurality of grip assemblies mounted on said mandrel and each projecting through a window in the housing, each of said assemblies having a slip member provided with a pair of longitudinally spaced wedge elements connected by an internal wall, said internal wall having an inner surface shaped for frictional contact with the outer surface of the mandrel, the wedge elements each having a serrated outer face, each assembly also having a dragblock member provided with an outer face, said outer face OF both members being shaped to engage the inner surface of a well casing, said dragblock member having a portion thereof laterally overlying said internal wall, resilient means confined between the internal wall of the slip member and the overlying portion of the dragblock member acting to hold said slip member in contact with the mandrel and the dragblock member in contact with the casing, interengaging parts on said housing and said dragblock member limiting the extent of outward movement of the dragblock member in the absence of the casing; means including slip-cone rings mounted on the mandrel for moving the slip members away from the mandrel against the action of the resilient means; screw thread means connecting the mandrel to one of said slip-cone rings; and means preventing relative turning movement of the housing and said slip-cone rings, while permitting relative axial movement therebetween.

7. The combination set forth in claim 6 in which the latter said means includes axially extending apertures in the housing each slidably receiving an element fixed on each of the slipcone rings, respectively.

8. The combination set forth in claim 6 in which the other of said slip-cone rings is connected to said mandrel by frangible means which may be sheared by upward movement of the mandrel relative to said slip-cone ring.

9. The combination set forth in claim 6 in which clearance regions are provided between the housing and the mandrel and between the slip-cone rings and the housing to provide gas passageways extending through the interior of the housing.

10. In a tubing anchor-catcher for securing a suing of tubing within a well casing, the combination of: a tubular mandrel having ends adapted to be connected to a tubing string and having an external screw thread; an annular housing mounted to turn on the mandrel and having circumferentially spaced window; axially spaced slip-cone rings mounted on the housing, one of the slip-cone rings having an internal screw thread engaging the external screw thread on the mandrel; means preventing relative turning movement but permitting relative axial movement of the housing and said slip-cone rings; a plurality of grip assemblies mounted on said mandrel and each projecting through a window in the housing, respectively, each of saidassemblies having a slip member provided with a pair of axially spaced wedge elements "engaged by the slip-cone rings, said wedge elements being connected by an internal wall, said wedge elements each having a serrated outer face, each grip assembly also having a dragblock member provided with a smooth outer face,- saidouter faces of both members being shaped to engage the inner surface of a well casing, the dragblock-member having axially spaced slots slidably receiving side edges of the slip member, said dragblock member having a bridge laterally overlying said'intemalwall, resilient means confined between said internal wall and the overlying bridge acting to move said slip memberradially toward the mandrel and the dragblock member radially inward toward the casing, and interengaging parts on said housing and said dragblockmember limiting the extent of outward movement ofthe dragblock member in the absence of the casing.

11. As a subcombination, a slip and dragblock assembly comprising: a dragblock member having parallel legs connected by a central transverse bridge to define longitudinal slots between the legs, a'slip member having a pair of wedge elements mounted at opposite ends of a connecting wall, each wedgeelement being slidably received in one of said slots, respectively, with said bridge overlying said wall, the dragblock member having an outer face, each wedge element having a serrated outer face, said outer faces each being shaped to engage the inner surface of a pipe, and resilient means confined between said bridge -and said wall acting to move said members in opposite directions.

12. The device set forth in claim 11 in which aligned sockets are provided on said bridge and said wall, and wherein said resilient means comprises coil compression springs mounted in the aligned sockets.

13. The device set forth in claim 11 in which the outer face of the dragblock member includes portions of said legs and said bridge.

14. In a device used to anchor and catch a tubing string, the combination of: a mandrel disposed within a housing, a plurality of circumferentially spaced friction drag elements car ried on said mandrel, a slip element behind each drag element and having a gripping portion extendible through an opening in the drag element into grippingcontact with a well conduit wall, spring means for urging said drag elements outward and said slip elements inward with respect to said housing, and expander means responsive to rotation of the mandrel for extending said gripping portions through said openings and into gripping contact with a well conduit wall.

15. In a tubing anchor-catcher for'securing a string of tubing within a well casing, the combination of: a tubing mandrel adapted to be connected to a tubing string; a housing encircling said mandrel; a plurality of grip assemblies mounted on said mandrel, each of said grip assemblies having a slip member and a dragblock member, the slip member having axially spaced wedge elements each provided with a serrated outer face, the slip member having a wall connecting said wedge elements, the dragblock member overlying the wall of the slip member and provided with an outer face, the outer faces of both members being shaped to engage the inner surface of a well casing, the slip member having an inner surface frictionally contacting the outer surface of said mandrel; interengaging parts on said housing and said dragblock member limiting the extent of outward movement of the dragblock member in the absence of the well casing; resilient means interposed between said members acting to hold the slip member against said mandrel and the dragblock member against the well casing; and expander means responsive to rotation of said mandrel for extending each slip member radially outward against the action of said resilient means.

16. As a subcombination, a slip and a dragblock assembly comprising: a slip member having a pair of wedge elements fixed at opposite ends of a connecting wall, the dragblock member being slidably received between said wedge elements said outer faces being shaped to engage the inner surface of a pipe, and resilient means confined between said wall and said dragblock member acting to move said members in opposite directions.

17. The device set forth in claim 16 in which spring alignment means are provided on said wall, and wherein said resilient means comprise coil compression springs engaging the alignment means.

18. In a device used to anchor and catch a tubing string, the combination of: a housing having circumferentially spaced windows, a mandrel disposed within the housing, a plurality of circumferentially spaced friction drag members carried on said mandrel and projecting through said windows, a slip member behind each drag member and having longitudinally spaced gripping portions confining the drag member between them, said gripping portions being extendable through the window of its respective drag member into contact with a well conduit wall, spring means for urging said drag members outward and said slip members inward with respect to said housing, and expander means responsive to rotation of said mandrel for extending said gripping portions through said windows and into gripping contact with the well conduit wall.

19. The combination set forth in claim 18 in which the expander means includes one cone element connected by threads to the mandrel and a second cone element connected by a shear ring to the mandrel.

it l l I t 

1. In a tubing anchor-catcher for securing a string of tubing within a well casing, the combination of: a tubular mandrel adapted to be connected to a tubing string; a plurality of grip assemblies mounted on said mandrel; each of said grip assemblies having a slip member provided with a pair of axially spaced wedge portions connected by an internal wall portion, the wedge portions each having a serrated outer face, each assembly also having a dragblock member provided with an outer face adapted to frictionally engage the inner surface of a well casing, means limiting the extent of outward movement of the dragblock member in the absence of the casing, resilient means confined between said wall portion of the slip member and said dragblock member acting to urge said slip member inwardly toward said mandrel and said dragblock member outward against the casing; and means for moving the slip members radially outward against the action of said resilient means and into gripping contact with the casing.
 2. In a tubing anchor-catcher for securing a string of tubing within a well casing, the combination of: a tubular mandrel adapted to be connected to a tubing string; a plurality of grip assemblies mounted on said mandrel; each of said grip assemblies having a slip member provided with a pair of axially spaced wedge portions connected by an internal wall portion, the wedge portions each having a serrated outer face, each assembly also having a dragblock member provided with an outer face adapted to frictionally engage the inner wall surface of a well casing, one of the members having at least one axially extending slot slidably receiving side edges of the other member, said dragblock member having a portion thereof laterally overlying said internal wall portion, means limiting the extent of outward movement of said dragblock member in the absence of the casing, resilient means confined between said wall portion of the slip member and the overlying portion of said dragblock member acting to urge said slip member inward toward said mandrel and said dragblock member outward against the casing; and means mounted on the mandrel for moving the slip members radially outward against the action of said resilient means and into gripping contact with the casing.
 3. The device set forth in claim 2 in which the dragblock member is provided with at least one slot which slidably receives side edges of one of the wedge portions of the slip member.
 4. The device set forth in claim 2 in which the dragblock member has two axially spaced slots slidably receiving side edges of the wedge portions of the slip member.
 5. The combination set forth in claim 2 in which said internal wall portion of said slip member has an inner surface adapted for frictional contact with the outer surface of said mandrel.
 6. In a tubing anchor-catcher for of a string of tubing within a well casing, the combination of: a tubular mandrel having ends adapted to be connected to a tubing string; an annular housing mounted to turn on the mandrel and provided with window; a plurality of grip assemblies mounted on said mandrel and each projecting through a window in the housing, each of said assemblies having a slip member provided with a pair of longitudinally spaced wedge elements connected by an internal wall, said internal wall having an inner surface shaped for frictional contact with the outer surface of the mandrel, The wedge elements each having a serrated outer face, each assembly also having a dragblock member provided with an outer face, said outer face OF both members being shaped to engage the inner surface of a well casing, said dragblock member having a portion thereof laterally overlying said internal wall, resilient means confined between the internal wall of the slip member and the overlying portion of the dragblock member acting to hold said slip member in contact with the mandrel and the dragblock member in contact with the casing, interengaging parts on said housing and said dragblock member limiting the extent of outward movement of the dragblock member in the absence of the casing; means including slip-cone rings mounted on the mandrel for moving the slip members away from the mandrel against the action of the resilient means; screw thread means connecting the mandrel to one of said slip-cone rings; and means preventing relative turning movement of the housing and said slip-cone rings, while permitting relative axial movement therebetween.
 7. The combination set forth in claim 6 in which the latter said means includes axially extending apertures in the housing each slidably receiving an element fixed on each of the slip-cone rings, respectively.
 8. The combination set forth in claim 6 in which the other of said slip-cone rings is connected to said mandrel by frangible means which may be sheared by upward movement of the mandrel relative to said slip-cone ring.
 9. The combination set forth in claim 6 in which clearance regions are provided between the housing and the mandrel and between the slip-cone rings and the housing to provide gas passageways extending through the interior of the housing.
 10. In a tubing anchor-catcher for securing a string of tubing within a well casing, the combination of: a tubular mandrel having ends adapted to be connected to a tubing string and having an external screw thread; an annular housing mounted to turn on the mandrel and having circumferentially spaced window; axially spaced slip-cone rings mounted on the housing, one of the slip-cone rings having an internal screw thread engaging the external screw thread on the mandrel; means preventing relative turning movement but permitting relative axial movement of the housing and said slip-cone rings; a plurality of grip assemblies mounted on said mandrel and each projecting through a window in the housing, respectively, each of said assemblies having a slip member provided with a pair of axially spaced wedge elements engaged by the slip-cone rings, said wedge elements being connected by an internal wall, said wedge elements each having a serrated outer face, each grip assembly also having a dragblock member provided with a smooth outer face, said outer faces of both members being shaped to engage the inner surface of a well casing, the dragblock member having axially spaced slots slidably receiving side edges of the slip member, said dragblock member having a bridge laterally overlying said internal wall, resilient means confined between said internal wall and the overlying bridge acting to move said slip member radially toward the mandrel and the dragblock member radially inward toward the casing, and interengaging parts on said housing and said dragblock member limiting the extent of outward movement of the dragblock member in the absence of the casing.
 11. As a subcombination, a slip and dragblock assembly comprising: a dragblock member having parallel legs connected by a central transverse bridge to define longitudinal slots between the legs, a slip member having a pair of wedge elements mounted at opposite ends of a connecting wall, each wedge element being slidably received in one of said slots, respectively, with said bridge overlying said wall, the dragblock member having an outer face, each wedge element having a serrated outer face, said outer faces each being shaped to engage the inner surface of a pipe, and resilient means confined between said bridge and said walL acting to move said members in opposite directions.
 12. The device set forth in claim 11 in which aligned sockets are provided on said bridge and said wall, and wherein said resilient means comprises coil compression springs mounted in the aligned sockets.
 13. The device set forth in claim 11 in which the outer face of the dragblock member includes portions of said legs and said bridge.
 14. In a device used to anchor and catch a tubing string, the combination of: a mandrel disposed within a housing, a plurality of circumferentially spaced friction drag elements carried on said mandrel, a slip element behind each drag element and having a gripping portion extendible through an opening in the drag element into gripping contact with a well conduit wall, spring means for urging said drag elements outward and said slip elements inward with respect to said housing, and expander means responsive to rotation of the mandrel for extending said gripping portions through said openings and into gripping contact with a well conduit wall.
 15. In a tubing anchor-catcher for securing a string of tubing within a well casing, the combination of: a tubing mandrel adapted to be connected to a tubing string; a housing encircling said mandrel; a plurality of grip assemblies mounted on said mandrel, each of said grip assemblies having a slip member and a dragblock member, the slip member having axially spaced wedge elements each provided with a serrated outer face, the slip member having a wall connecting said wedge elements, the dragblock member overlying the wall of the slip member and provided with an outer face, the outer faces of both members being shaped to engage the inner surface of a well casing, the slip member having an inner surface frictionally contacting the outer surface of said mandrel; interengaging parts on said housing and said dragblock member limiting the extent of outward movement of the dragblock member in the absence of the well casing; resilient means interposed between said members acting to hold the slip member against said mandrel and the dragblock member against the well casing; and expander means responsive to rotation of said mandrel for extending each slip member radially outward against the action of said resilient means.
 16. As a subcombination, a slip and a dragblock assembly comprising: a slip member having a pair of wedge elements fixed at opposite ends of a connecting wall, the dragblock member being slidably received between said wedge elements and overlying said wall, the dragblock member having an outer face, each wedge element having a serrated outer face, said outer faces being shaped to engage the inner surface of a pipe, and resilient means confined between said wall and said dragblock member acting to move said members in opposite directions.
 17. The device set forth in claim 16 in which spring alignment means are provided on said wall, and wherein said resilient means comprise coil compression springs engaging the alignment means.
 18. In a device used to anchor and catch a tubing string, the combination of: a housing having circumferentially spaced windows, a mandrel disposed within the housing, a plurality of circumferentially spaced friction drag members carried on said mandrel and projecting through said windows, a slip member behind each drag member and having longitudinally spaced gripping portions confining the drag member between them, said gripping portions being extendable through the window of its respective drag member into contact with a well conduit wall, spring means for urging said drag members outward and said slip members inward with respect to said housing, and expander means responsive to rotation of said mandrel for extending said gripping portions through said windows and into gripping contact with the well conduit wall.
 19. The combination set forth in claim 18 in which the expander means includes one cone element connected by threads to the mandrel and a second cone element connected by a shear ring to tHe mandrel. 